This present invention relates to a system for conveying solids materials. More particularly, this invention relates to a conveying system which is capable of transporting compacted, friable solids materials, particularly partial oxidation (POX) carbon, without mechanically pushing or compressing the solids material.
Partial oxidation (POX) carbon requires being transported from a bed of agglomerated POX carbon particles to a container, incinerator or other location which can be at a higher pressure than the pick-up location. Incineration of the POX carbon requires storage and subsequent transport of the POX carbon to the incinerator. POX carbon is a material with unusual properties. It is a powder which appears dry but consists of 80 to 90% free water contained inside a spherical structure of carbon. The powder is friable and easily separates when agglomerated particles are pulled apart. However, it behaves like a solid mass when pushed or compressed.
Because of its physical properties, conventional solids handling equipment that push or compress handled material cannot be used to handle POX carbon. Screw conveyors, drag chain conveyors, rotary feeders, and the like, have been found to cause the POX carbon to compress into a solid mass and, therefore, have not been able to provide reliable, plug free conveyance of the friable POX carbon material.
Therefore, it is an object of the present invention to provide a novel robotic handling and pneumatic/gas conveying system which is capable of transporting particles of friable, non-free-flowing solids materials, such as POX carbon, using a conveying system that does not push or compress the solids material during transport. That is, the gas conveying system of the present invention provides accelerating and impact forces that are relatively mild compared to other conventional material handling technologies.
It is still a further object of the present invention to provide a unique material conveying system wherein no moving parts contact the material being transported there-through.
It is also an object of the present invention to provide a unique end effector (i.e., a robotic-guided vacuum pick-up lance) which comprises a cutting blade, vacuum pick-up, and mechanical lump breaker (or any other device capable of breaking-up the solid mass and allowing it to flow in a controlled manner into the vacuum gas stream for down-stream conveying). This end effector is capable of slicing a section of the friable material from a compressed bed thereof, and mechanically breaking or mashing the slice into particles that can then be readily transported through the conveyor system without causing plugging.
Finally, it is an object of the conveyor system according to the present invention to use co-axial eductors which allows the solids material to be conveyed such that it passes in a straight line through the eductor, thus avoiding the requirement of conventional eductors where the solids material must experience a turn of up to about 90 degrees during transporting.
The present invention is directed to a two-stage air or other gas-conveying system for conveying particles of a friable material without pushing or compressing the particles into a solid mass. This unique two-stage pneumatic/gas conveying process or system is capable of transporting POX carbon from a bed of agglomerated POX carbon particles to a container, incinerator, or other location which can be at a higher pressure than the pick-up location. Although especially useful for conveying particles of friable material, the present two-stage gas-conveying system can also be advantageously used to transport other particulate matter.
The pneumatic (or other gas) conveying system comprises: at least one conduit assembly comprising a conduit, a fragmentation device about a first end of the conduit which is capable of removing the solids material (e.g., partial oxidation carbon) from a holding container, and a first eductor which is capable of entraining the solids material in a gas stream and moving the solids material through the conduit; a separator (i.e., a cyclone or other gas-solids separation device) disposed about a second end of the conduit, the separator being capable of separating the solids material from the gas stream; and a second eductor disposed to receive the solids material from the separator, the second eductor being capable of entraining the solids material in a second gas stream which has a solid-material-to-gas mass ratio which is greater than that of the first eductor.
The second eductor is preferably capable of transporting the solids material downstream for either storage, treatment, or further transport. A preferred method of treatment includes incinerating the POX carbon in an incinerator.
It is also preferable to provide an acceleration spool between the cyclone (or other gas separation device) and the second eductor. The acceleration spool is capable of accelerating the solids material and gas expelled from the bottom of the cyclone. The cyclone typically includes an inlet and outlet, wherein the cyclone includes a device for preventing the plugging of the inlet. Preferably, the device is a carbon steel antifouling baffle. Cyclone separators are known in the art and a general discussion of such is found in Perry""s Chemical Engineers Handbook, 7th Edition (1997) at pages 17-27 to 17-32, the entirety of which is hereby incorporated by reference.
The first eductor and second eductors preferably produce discharge pressures that are up to about 20.6 KPa above the eductor inlet pressure, when the pressure of the motive fluid applied to the eductors is about 7.9 bar. When a higher pressure motive fluid is used, the eductor discharge pressure will also be higher. The solid-material-to-gas mass ratio of the first eductor is between about 0.5:1 to 1.5:1; whereas the solid-material-to-gas mass ratio of the second eductor is between about 1:1 to 4:1. The first eductor and second eductor are compressed air (or gas)-driven coaxial eductors.
The fragmentation device disposed about a first end of the conduit is capable of removing the solids material from a holding container can be any device which is capable of removing solids material from a holding container. Preferably, the fragmentation device is also capable of removing by, for example, scraping off a portion of the compressed block of solids material. The fragmentation device is more preferably a novel lance assembly which comprises: a cutting blade/scraper which is capable of separating a portion of the solids material from a compressed block of the solids material and/or crushing the portion of the solids material into particles of a predetermined size which may be transported via the conduit assembly. Other examples of fragmentation devices suitable for use in the current invention include a mechanical rotary device with protruding arms, such as a rototiller-like device; a rotating blade device similar to a rotary-blade or reel-type lawnmower; or a vibrating-blade or reciprocating-blade device. Any of which is capable of breaking a solid block of material into smaller particles.
Each system preferably comprises a positioner (i.e., a robotic guide) which is capable of positioning a lower end of the lance assembly below a surface of the solids material in the holding container and moving the lance assembly in a predetermined pattern through the holding container.